In general, lithium-containing transition metal oxides are used for a positive electrode active material for lithium ion batteries. In particular, they are lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganite (LiMn2O4) and the like. A conjugation of the lithium-containing transition metal oxides is proceeding in order to improve properties such as high volume, cycle characteristic, storage characteristic, decreased internal resistance, rate performance, and safety. Lithium ion batteries, for large-size equipment use such as automobile use and load leveling use, require properties different from those of the past mobile phone use and personal computer use.
Traditionally, various methods have been conducted for improving the rate performance. For example, patent document 1 discloses a manufacturing method of a positive electrode material for a lithium secondary battery characterized in that a lithium-nickel composite oxide having a composition of LixNi1−yMyO2−δ (0.8≤x≤1.3, 0<y≤0.5, M is at least one element selected from a group consisting of Co, Mn, Fe, Cr, V, Ti, Cu, Al, Ga, Bi, Sn, Zn, Mg, Ge, Nb, Ta, Be, B, Ca, Sc and Zr. δ is oxygen loss or oxygen excess, −0.1<δ<0.1) is passed through a classifier to separate particles having large particle diameters from particles having small particle diameters by equilibrium separation particle size Dh=1 to 10 μm, and the particles having large particle diameters are mixed with the particles having small particle diameters at weight ratios of 0:100 to 100:0, and the method can easily produce a positive electrode material for a lithium secondary battery having various balance of rate performance and capacity.
(Patent documents 1) Japanese Patent No. 4175026